III-V/Si Hybrid MOS Optical Phase Shifter for Si Photonic Integrated Circuits
III-V/Si Hybrid MOS Optical Phase Shifter for Si Photonic Integrated Circuits
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用于硅光子集成电路的 III-V/Si 混合 MOS 光学移相器
DOI：
10.1109/jlt.2019.2892752
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发表时间：
2019
影响因子：
4.7
通讯作者：
Takagi Shinichi
中科院分区：
文献类型：
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作者：
Takenaka Mitsuru;Han Jae-Hoon;Boeuf Frederic;Park Jin-Kwon;Li Qiang;Ho Chong Pei;Lyu Dongsheng;Ohno Shuhei;Fujikata Junichi;Takahashi Shigeki;Takagi Shinichi
我们提出了一种新的光相位调制方案上的Si光子平台，使用III-V/Si混合金属氧化物半导体（MOS）电容器形成的n型InGaAsP膜上的p型Si波导。数值计算表明，当用n型InGaAsP层代替Si MOS光移相器中的n型Si层时，由于InGaAsP MOS界面处的电子积累，相位调制效率提高了7-8倍。为了实现III-V/Si混合MOS电容器，我们开发了一种通过原子层沉积法沉积的Al_2O_3键合界面，使InGaAsP MOS界面处的界面陷阱密度低于10^12 cm^-2·eV^-1，这对电子积累至关重要。在1.55 μm波长处，由于InGaAsP的折射率发生了电子诱导的变化，调制效率达到了0.047 V·cm。由于在III-V/Si混合MOS电容器的III-V层中没有诱导空穴，因此避免了InGaAsP中的大的空穴诱导吸收。结果，当我们有π相移时，我们获得了0.23 dB的光吸收，比Si MOS光移相器的光吸收小大约十倍。通过数值分析发现，这种高效低损耗的III-V/Si混合MOS光移相器显著提高了光调制幅度，适用于100 Gb/s以上的高速调制。我们还演示了马赫-曾德尔干涉仪光开关使用建议的光移相器与开关时间小于20纳秒。我们实现了约1 nW的极低开关功率，从而实现了大规模光开关和通用光子集成电路。我们还讨论了光子神经网络用于深度学习的可行性。
We present a novel optical phase modulation scheme on a Si photonic platform that uses a III–V/Si hybrid metal–oxide–semiconductor (MOS) capacitor formed by bonding an n-type InGaAsP membrane on a p-type Si waveguide. We numerically revealed that the phase modulation efficiency was improved by a factor of 7–8 owing to electron accumulation at the InGaAsP MOS interface when the n-type Si layer in a Si MOS optical phase shifter was replaced by an n-type InGaAsP layer. To realize the III–V/Si hybrid MOS capacitor, we developed an Al_2O_3 bonding interface deposited by atomic layer deposition that enabled a low interface trap density of <10^12 cm^–2·eV^–1 at an InGaAsP MOS interface, which was essential for electron accumulation. We demonstrated a modulation efficiency of 0.047 V·cm at 1.55-μm wavelength owing to the electron-induced change in the refractive index of InGaAsP. Since no holes were induced in the III–V layer of the III–V/Si hybrid MOS capacitor, we avoided large hole-induced absorption in InGaAsP. As a result, when we had a π phase shift, we obtained optical absorption of 0.23 dB, approximately ten times smaller than that of a Si MOS optical phase shifter. We found by numerical analysis that the efficient low-loss III–V/Si hybrid MOS optical phase shifter improved markedly the optical modulation amplitude, indicating its suitability for high-speed modulation beyond 100 Gb/s. We also demonstrated a Mach–Zehnder interferometer optical switch using the proposed optical phase shifter with a switching time of less than 20 ns. We achieved an extremely low switching power of approximately 1 nW, enabling a large-scale optical switch and universal photonic integrated circuits. We also discuss the feasibility of a photonic neural network for deep learning.